It is known in the art for airbag inflation systems to utilize a battery or other power source to drive a circuit in order to fire an inflator under prescribed conditions, thereby inflating the airbag. The inflator is fired when acceleration switches, used to detect an impact, allow the current from the battery or other power source to flow through the circuit to an initiator, or squib, charges the initiator, which then ignites the inflator.
The integrity, or “health” of the circuit and, most importantly, of the squib, is paramount to the proper operation of the airbag in a crash event. If any part of the circuit fails, or if the squib itself fails, then the inflator will not fire and the airbag will not deploy.
The problem is that these circuits are typically “blind” systems. There is often no simple way to test the integrity of the system without inadvertently deploying the airbag.
Previous attempts to address this problem have incorporated diagnostic means that impose a power drain on the system while inactive. For battery powered airbag systems, such as those employed in aircraft, it is not desirable to have a diagnostic means that also drains the battery while not in use. Current attempts in the art have suffered from this problem where the continuous current draw drains the battery, rendering the firing system inoperable when it is needed the most—in a crash event. Other attempts in the prior art include a required second source of electrical energy in the monitoring and diagnostic circuit in addition to the primary electrical energy source used to power the firing system.
Other attempts to diagnose the integrity of the firing system fall short because they are not able to detect shorts or opens at individual squibs. This is a problem in systems where one electronic control module (ECM) may control the firing of multiple airbags. This is typically the situation in airbag systems for aircraft where one ECM may be used to deploy multiple airbags, one or more on each of a row of seats.
It would, therefore, be desirable to have a system and related method for diagnosing initiators in airbag systems where one, or more than one, initiator may be diagnosed individually, shorts or opens may be detected, with no power drain while inactive and without the need for a second source of electrical energy.
While certain aspects of conventional technologies and methods in the relevant art have been discussed to facilitate disclosure of the invention, Applicant in no way disclaims these technical aspects or methods, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects or methods discussed herein.
In this specification, where a document, act, or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act, or item of knowledge or any combination thereof was, at the priority date, publicly available, known to the public, part of common general knowledge, or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which this specification is concerned.